C-Sulfonylation of 4-Alkylpyridines: Formal Picolyl C-H Activation via Alkylidene Dihydropyridine Intermediates

J Org Chem. 2023 Mar 17;88(6):3998-4002. doi: 10.1021/acs.joc.3c00017. Epub 2023 Feb 27.

Abstract

4-Picoline derivatives are converted to the corresponding aryl picolyl sulfones upon treatment with aryl sulfonyl chlorides and Et3N in the presence of catalytic DMAP. The reaction proceeds smoothly for a variety of alkyl and aryl picolines using a range of aryl sulfonyl chlorides. The reaction is believed to involve N-sulfonyl 4-alkylidene dihydropyridine intermediates and results in formal sulfonylation of unactivated picolyl C-H bonds.